Global warming: a few skeptics still ask why it's happening

With alarms bells over global warming ringing ever louder and more insistent, is it possible – or credible – for an active scientist working on climate questions to be skeptical of the cause or future severity?

Amid mounting evidence that temperatures are rising on planet Earth, the "skeptics" and "agnostics" are a smaller band than they used to be. Yet those who do still harbor doubts about a looming global-warming crisis are quietly continuing to test alternative ideas about how climate works and what, if not the burning of fossil fuels, might be causing the temperature creep.

This week some of the doubters testified at a Senate hearing on global warming, perhaps their last chance to take the bully pulpit for at least two years, now that Congress is shifting to Democratic control. At a hearing chaired by Sen. James Inhofe (R) of Oklahoma, who has dismissed warnings of a global-warming crisis as a hoax, they expressed misgivings about the reliability of climate forecasts and questioned whether the current warming even is unusual, among other things.

These objections are not new, and many environmentalists and scientists say research has already passed them by. Moreover, they distract from the urgent need to get on with curbing emissions of carbon dioxide and other greenhouse gases.

Yet even critics acknowledge that science is a discipline that needs its maverick thinkers – and that the global-warming skeptics and their research provide a kind of reality check on the climatology field. They acknowledge, too, that scientific training, temperament, and field of specialty factor into the motivations of researchers who retain reservations about human-induced climate change.